package cn.tedu.em.user.webapi.filter;

import cn.tedu.em.common.restful.JsonResult;
import cn.tedu.em.common.restful.ResponseCode;
import cn.tedu.em.user.webapi.security.LoginPrincipal;
import com.alibaba.fastjson.JSON;
import io.jsonwebtoken.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

@Slf4j
@Component
public class JwtAuthorizationFilter extends OncePerRequestFilter {

    @Value("${em.jwt.secret-key}")
    private String secretKey;

    /**
     * JWT的最小长度值
     */
    public static final int JWT_MIN_LENGTH = 113;

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse
            response, FilterChain filterChain) throws ServletException, IOException {
        log.debug("JWT过滤器开始执行...");
        String jwt = request.getHeader("Authorization");
        log.debug("客户端携带的JWT: {}", jwt);

        if (!StringUtils.hasText(jwt) || jwt.length() < JWT_MIN_LENGTH){
            log.debug("客户端没有携带有效的JWT,将放行,由后续的过滤器等组件继续处理此请求......");
            filterChain.doFilter(request,response);
            return;
        }

        Claims claims = null;
        response.setContentType("application/json; charset=utf-8");
        try {
            claims = Jwts.parser().setSigningKey(secretKey).parseClaimsJws(jwt).getBody();
        } catch (MalformedJwtException e) {
            String message = "非法访问!";
            log.warn("解析JWT时出现MalformedJwtException, 将响应错误消息: {}",message);
            PrintWriter writer = response.getWriter();
            JsonResult<Void> jsonResult = JsonResult.failed(ResponseCode.BAD_REQUEST,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        } catch (SignatureException e) {
            String message = "非法访问!";
            log.warn("解析JWT时出现SignatureException, 将响应错误消息: {}",message);
            PrintWriter writer = response.getWriter();
            JsonResult<Void> jsonResult = JsonResult.failed(ResponseCode.BAD_REQUEST,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        } catch (ExpiredJwtException e) {
            String message = "您的登录已过期,请重新登录!";
            log.warn("解析JWT时出现ExpiredJwtException, 将响应错误消息: {}",message);
            PrintWriter writer = response.getWriter();
            JsonResult<Void> jsonResult = JsonResult.failed(ResponseCode.BAD_REQUEST,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        } catch (Throwable e) {
            String message = "服务器忙，请稍后再次尝试！（开发过程中，如果看到此提示，请检查控制台的信息，并补充处理异常的方法）";
            log.warn("解析JWT时出现Throwable, 将响应错误消息: {}",message);
            log.warn("异常类型：{}", e.getClass());
            log.warn("异常信息：{}", e.getMessage());
            e.printStackTrace();
            PrintWriter writer = response.getWriter();
            JsonResult<Void> jsonResult = JsonResult.failed(ResponseCode.INTERNAL_SERVER_ERROR,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        }
        Long id = claims.get("id", Long.class);
        String username = claims.get("username", String.class);
        String authoritiesJsonString = claims.get("authoritiesJsonString", String.class);
        log.debug("解析JWT结束, id={}, username={}",id,username);

        LoginPrincipal loginPrincipal = new LoginPrincipal();
        loginPrincipal.setId(id);
        loginPrincipal.setUsername(username);

        List<SimpleGrantedAuthority> authorities = JSON.parseArray(authoritiesJsonString, SimpleGrantedAuthority.class);
        log.debug("将JWT中的权限列表的JSON字符串解析为List<GrantedAuthority>类型，结果：{}", authorities);

        Object principal = loginPrincipal;
        Object credentials = null;
        Authentication authentication = new UsernamePasswordAuthenticationToken(principal,credentials,authorities);
        log.debug("即将存入到SecurityContext中的Authentication对象：{}", authentication);

        SecurityContext securityContext = SecurityContextHolder.getContext();
        securityContext.setAuthentication(authentication);
        log.debug("已经将Authentication对象存入到SecurityContext");

        log.debug("JWT过滤器执行完毕，将放行");
        filterChain.doFilter(request,response);
    }
}
